Rontgen tube and manufacture of same



-;-Nov. s, 1927.

A. F. WUROMUS RGNTGEN TUBE AND MANUFACTURE OF SAME Filed J1 11.v 25,1925 In men tor:

fizif Patented Nov. 8, 1927 UNITED STATES PATENT OFFICE.

ARTHUR FRITZ WUROMU'S, OF BERLIN-ZEHLENDORF, GERMANY, ASSIG-NOR TO THEFIRM SENDLINGER OPTISGHE GLAS'WERKE G. IVE. 1-11, 015BERLIN-ZEHLENDO'RF,

GERMANY.

RfiNTGEN TUBE AND MANUFACTURE OF SAME.

Application fi1ed'J'u1y25, 1925, Serial ,No. 45,997, and in Ger-manyJuly 31, 1924.

This invention'has reference to B6ntgen tubes and it is particularlyintended .to provide a tube of the kind referred to which, whilepresenting highly .efiicient vacuum qualities, is substantiallyprotected from undesired Rontgen radiations. In accordance therewith itis one of the important objects of this invention to provide a bulb ofhigh vacuum glass permeable for Bontgen ral0 diation which kind of glassin the interest of brevity may be .called hereafter a high vacuumltontgen glass, with a glass coating substantial-1y impermeable forRontgen radiation, which if required, maybe eifected by means of theinsertion of intermediate transitionglass layers, the said coating orenvelope of glass being melted onto the glass base so that the tubeconstitutes a unitary glass body with its envelopeof a protecting glasslayer. Broadly considered, it s suffi- .cient to coat an ordinaryRontgen high vacuum glass with an enveloping glass coating of similarheat expansion and of sufiicient percentage of lead contents andvwithout the .use of transition glass layers between the inner and outerlayers. A compound Rontgen glass tube of this description pre sents theadvantage as compared with the well known tubes with protecting -la:yers

so loosely disposed upon-the glass base that it presents an increasedresistency against fracture and kicking through of the insulation.

The window for admittingas undisturbed as possible a discharge of therayswhich is required in the case of tubes with protective layer isformed in the tube in accordance with this invention in the preferredconstrue itlOIl by an interruption of the continuity of the surface ofthe exterior envelope provduced by the Rontgen protective glass. Themanufacture of the window is preferably carried out in accordance withmy invention by the grinding oil or etching of the glass coating at theparticular places. Instead of leaving this window in the glass .coatingexposed, it may be closed by aspecial window inserted therein and whichis transparent for Rontgen rays.

The window may also be produced by providing the compound tube with anaperture which not onlypasses through the enveloping and protectingglass coating, but through the high vacuum glass as well and by thenclosing this aperture by a window of a suitable kind of glass.

In further pursuance of my invention, the protecting glass coating maybe colored, whenever required, in order to reduce the possibility of theescape of visiblerays from the tube, if desired. The light absorbingcolored envelope may alsoconstitute an .intermediate layer between thehigh vacuum glass and the enveloping and protecting glass coating. Thecoloration of this glass envelope presents the vadditional advantagefrom the point of view of manufacture that by this means it can beeasily ascertained at what moment the protecting layer at the pointcorresponding to the window has been completely removed in the grindingout of the window on the tube forthe passage of the Rontgen rays. 7

The. invention will .be further described with reference to theaccompanying drawing showing by way of exemplification an embodimentthereof in connection with a Rontgen tube in Fig. 1 in longitudinalsection, while Figs. 2 and. 3 are fractional views to illustrate theproduction of an interruption of continuity in the tube for the purposeof providing the same with a window.

In the drawings the high vacuum tube is indicated conventionally at 1 itdoes ,not need to possess very thick walls, inasmuch as the mechanicalstrength of the tube isinsured by the protecting coating 2 which, in

order to perform a sufficient protecting action, should at least possessa thickness of,

for instance, 10 millimeters.

In accordance with the illustration of Fig. 1., the protecting glasscoating is provided with a window 3, while the high vacuum tube 1 iscompletely continuous and not .interrupted by a window or the like. The

cathode of the tube is indicated at 4: and the anticathode at 5.' Thewindow 3 in the protectingcOatingQ may be produced by grinding. Thisprotecting coating 2 may consist of colored glass in order to reduce theescape of rays oflight.

Tnsteadof producing the window, as in the form of construction inaccordance withFig. l, by grinding or by the etching off oftheenveloping coating, an interruption of the glass coating may also beproduced, as indicated in Fig. 2, in the blowing of the tube byemploying a mould 6 wit-h an opening 7 at a suitable point thereof andwithin which a plunger or the like 8 is adapted to be displaced. As soonas the blowing in the mould 6 is nearly completed, the plunger 8 is withdrawn and the glass, while still in a soft condition, projects into thethen exposed aperture 7, so that a boss is produced which facilitatesthe grinding operation. The grinding off, when a boss or swelling ofthis kind has been provided, may easily be carried so far that aninterruption is not only produced in the layer of protectingcoating 2,but also in the high vacuum glass 1*, whereupon the opening thusproduced in the layer l is closed by the welding of a suitable glassplate onto the edge of the opening in the high vacuum glass.

liVhenever desired, the window 9 may also be given filtering propertiesfor soft Rontgen rays by manufacturing it of a suitable kind of glass,thus for instance of a glass with a suitable content of oxides of metalsof high atomic weight, such for instance lead, zinc, barium or the like.

'In further pursuance of the invention the .opening 3 in the protectingenvelope of the exemplification according to Fig. '1 may likewise beclosed by a window having suitable filtering properties. l/Vhenproceeding in this manner, it is preferable to arrange the filteringaction in accordancewith the minimal filters suggested by law for translumination.

A tube manufactured in accordance with this invention is not onlyadapted to admit of the generation of a very high vacuum on accountofthe particular nature of the interior glass selected in view of thehigh vacuum desired, but it also possesses very high mechanical strengthin view of the strong exterior protective envelope and, though in viewof the thick protective layer it is of course heavier than the ordinaryRo'ntgen tube of high vacuum glass, it is easier of manipulation owingto the possibility of dispensing with the necessity of a specialprotective hood, which in turn results in an appreciable reduction ofthe total weight of the Rontgen arrangement. The tube, moreover,possesses highly favorable electric properties, both as regards itssafety from sliding sparks as well as from kicking through or breakingof the insulation, the more so, since any possible bubbles and streakspresent in the glass are not injurious in view of the great thickness ofthe protecting layer. It therefore becomes unnecessary to assert theproduct in accordance with the presence of bubbles and streaks, so thatthe manufacturer has only to take into account any possible waste inconsequence of the manufacture of the window.

As compared with an' ordinary lead glass tube, the compound tubehereinbefore described presents the advantage that, in view of the highsoftening point of the Rontgen glass which is several hundred degreesabove that of the lead glass, the new product of manufacture is betteradapted to withstand the temperature strains occurring in a glow ingcathode tube.

It should be understood in this connection that, while the invention hasbeen shown and described for purposes of illustration in connection witha preferred embodiment, it is not restricted thereto, but it issusceptible of modifications and changes in accordance with varyingconditions, of application and the convenience of the operator, andwithout deviatin from the spirit of the invention, as partic arlypointed out in the appended claims;

I claim:' y

1. The method of manufacturing a Rontgen tube, which consists in meltingonto a tube of high vacuum Rontgen glass an outer protective glassenvelope and providin an interruption of continuity in said enve ope.

2. The method of manufacturing a Rom;- gen tube, which consists inmelting onto a tube of high vacuum Rontgen glass an outer protectiveglass envelope removing a certain field from said protective envelopeand closing the same by glass adapted to allow the escape of Rontgenrays.

3. As a new article of manufacture a glass bulb for a Rontgen tubehaving a compound wall comprising an inner layer of high vacuum glasspermeable for Rontgen' radiation and an outer layer having protectivequalities against Rontgen radiation, the layers being in weldingconnection with each other.

4;. As a new article of manufacture a glass bulb for a Rontgen tubehaving a compound wall comprising a thin inner layer of high vacuumglass permeable for Rontgen radiation and a considerablythicker outerlayer having protective qualities against Rontgen radiation, the layersbeing in welding connection with each other. I

5. As anew article of manufacture a glass bulb for a R'ontgen tubehaving a compound wall comprising athin inner layer of high tion and aconsiderablythicker outer layer having protective qualities againstRent-gen radiation and being locally interrupted so as toallow escape ofRontgen rays through the interruption, the layers being in weldingconnection with each other.

6.As a new article of manufacture a Rontgen tube having a compound glasswall, the inner layer consisting of a high vacuum glass permeable forRontgen radiation and the outer of a kind of glass having protectivequalities for Rontgen radiation the outg-layer being materially thickerthan the inner and being in welding connection therevacuum glasspermeable for Rontgenradiawith, an interruption being provided thereinfor the escape of Rontgen rays.

7. As a new article of manufacture, a Rontgen tube provided with a fieldof different glass adapted for the escape of Rontgen rays the tubefurther provided with an outer protective glass coating integraltherewith said coating provided with a window registering with the fieldof different glass in the tube.

8. The method of manufacturing Rontgen tubes and the like, whichconsists in melting onto a tube of high vacuum Rentgen glass an outerprotective glass envelope, and removing a distinct field from saidenvelope.

In testimony whereof I have signed this specification.

ARTHUR FRITZ WVUR-OMUS.

